Ipod + Headroom Total Airhead

I am thinking of buying a total airhead amp to use with my ipod nano. I dont want to use the headphone jack on the ipod and was looking at this cable iPod Docking Connector to 3.5mm(1/8")Stereo Audio Cable. Do I also need a DAC with this or will it work going straight into the airhead?

You will be bypassing the amplification stage in the ipod and sending a line level input into the airhead. This will avoid double amping. The only way to get digital output from an ipod is the wadia itransport.